Apparatus and methods to adjust ocular blood flow

Abstract

An apparatus to treat, inhibit, or prevent an eye condition in a patient can include a cover, sized and shaped to fit over an eye of a patient to define a cavity between the cover and an anterior surface of the eye when the cover is located over the patient eye. The apparatus can include a pressure source, in communication with the cavity, capable of applying non-ambient pressure in the cavity. The apparatus can include control circuitry, in communication with the pressure source, configured to vary non-ambient pressure applied to the cavity to affect a targeted pressure relationship between an indication of a first physiological pressure level and a second physiological pressure level associated with the eye of the patient.

What is claimed is: 
     
       1. An apparatus to generate an indication of an ocular autoregulation (OA) index to characterize an autoregulation capability of an eye of a patient, the OA index characterized by at least two OA values, wherein an individual one of the at least two OA values includes an ordered pair relationship of an indication of ocular perfusion pressure (OPP) in the eye and an indication of blood flow in the eye, the apparatus comprising:
 a cover, sized and shaped to fit over the eye to define a cavity between the cover and an anterior surface of the eye; 
 a pressure source, in communication with the cavity, configured to adjust fluid pressure in the cavity to affect the indication of OPP; and 
 control circuitry, in communication with the pressure source, the control circuitry configured to: 
 apply a first control signal to the pressure source to generate a first pressure in the cavity corresponding to a first indication of intraocular pressure (IOP) in the eye; 
 receive the first indication of IOP in the eye and a first indication of systemic blood pressure in the patient to calculate a first indication of OPP and a first indication of blood flow in the eye associated with the first indication of OPP to form a first OA value; 
 apply a second control signal to the pressure source to generate a different second pressure in the cavity corresponding to a second indication of IOP in the eye; 
 receive the second indication of IOP in the eye and a second indication of systemic blood pressure in the patient to calculate a second indication of OPP and a second indication of blood flow in the eye associated with the second indication of OPP to form a second OA value; and 
 calculate an OA index of the eye based upon the first OA value and the second OA value. 
 
     
     
       2. The apparatus of  claim 1 , wherein an indication of OPP includes a difference between an indication of systemic blood pressure in the patient and an indication of intraocular pressure (IOP) in the eye. 
     
     
       3. The apparatus of  claim 1 , wherein an indication of OPP includes a central tendency of OPP. 
     
     
       4. The apparatus of  claim 1 , wherein an indication of blood flow in the eye includes an indication of blood flow sensed by an ocular blood flow sensor. 
     
     
       5. The apparatus of  claim 4 , wherein the ocular blood flow sensor includes an ultrasonic sensor. 
     
     
       6. The apparatus of  claim 4 , wherein the ocular blood flow sensor includes a charge coupled device (CCD). 
     
     
       7. The apparatus of  claim 4 , wherein the ocular blood flow sensor includes a Doppler imaging system. 
     
     
       8. The apparatus of  claim 4 , wherein the ocular blood flow sensor includes a laser speckle flowgraphy (LSF) system. 
     
     
       9. The apparatus of  claim 4 , wherein the ocular blood flow sensor includes a laser speckle contrast imaging (LSCI) system. 
     
     
       10. The apparatus of  claim 4 , wherein the ocular blood flow sensor includes a laser Doppler flowmeter (LDF). 
     
     
       11. The apparatus of  claim 4 , wherein the ocular blood flow sensor includes an ocular coherence tomography angiography (ICTA) system. 
     
     
       12. The apparatus of  claim 4 , wherein the ocular blood flow sensor includes a laser Doppler velocimetry (LDV) system. 
     
     
       13. The apparatus of  claim 4 , wherein the ocular blood flow sensor includes a pattern electroretinography (PERG) test. 
     
     
       14. The apparatus of  claim 1 , wherein the control circuitry is configured to determine an OA capability line that is characterized by at least two OA values, and wherein the OA index is determined using a slope of the OA capability line. 
     
     
       15. The apparatus of  claim 1 , wherein the control circuitry is configured to determine an OA capability line that is characterized by at least two OA values, and wherein the OA index includes a length of the OA capability line. 
     
     
       16. A method of generating an indication of an ocular autoregulation (OA) index to characterize an autoregulation capability of an eye of a patient, the OA index characterized by at least two OA values, wherein an individual one of the at least two OA values includes an ordered pair relationship of an indication of ocular perfusion pressure (OPP) in the eye and an indication of blood flow in the eye, the method comprising:
 applying a first cavity pressure in a cavity between a cover and an anterior surface of the eye to generate a first IOP; 
 measuring, at the first IOP, a first indication of OPP and a first indication of blood flow in the eye to form a first OA value; 
 applying a second cavity pressure in a cavity between a cover and an anterior surface of an eye to generate a second IOP; 
 measuring, at the second IOP, a second indication of OPP and a second indication of blood flow in the eye to form a second OA value; and 
 calculating an OA index based upon the first OA value and the second OA value. 
 
     
     
       17. The method of  claim 16 , wherein measuring a first indication of OPP includes measuring a first indication of IOP from the eye and a first indication of systemic blood pressure in the patient at the first cavity pressure and wherein measuring a second indication of OPP includes measuring a second indication of IOP from the eye and a second indication of systemic blood pressure in the patient at the second cavity pressure. 
     
     
       18. The method of  claim 17 , wherein measuring a first indication of OPP includes calculating the first indication of OPP from the measured first indication of IOP and the measured first indication of systemic blood pressure and wherein measuring a second indication of OPP includes calculating the second indication of OPP from the measured second indication of TOP and the second measured indication of systemic blood pressure. 
     
     
       19. The method of  claim 16 , wherein calculating an OA index includes determining an OA capability line characterized by at least two OA values and determining the OA index from a slope of the OA capability line. 
     
     
       20. The method of  claim 16 , wherein calculating an OA index includes determining a capability line characterized by at least two OA values and determining the OA index from a length of the capability line.